Why a simple kiss is so telling How humans lock lips holds the key to our hearts — and so much more

What happens during that first kiss can be a make-or-break proposition. "A kiss is a blast of information that you are sending out and information that you are receiving," "Basically it's a mate assessment tool. Much of the cortex is devoted to picking up sensations from around the lips, cheeks, tongue and nose. Out of 12 cranial nerves, five of them are picking up the data from around the mouth. "It is built to pick up the most sensitive feelings -- the most intricate tastes and smells and touch and temperature. And when you're kissing somebody, you can really hear them and see them and feel them. So kissing is not just kissing. It is a profound advertisement of who you are, what you want and what you can give."

"kissing is so powerful for females that even though they deny it, once it occurs, they're so affected by a kiss . . ." That they're helpless in its grip? "Yup."

By Joel GarreauThe Washington Post / Feb. 14, 2009

WASHINGTON - Okay, so: kissing. Here's what we know.

It has major evolutionary advantage. Only the hottest and highest species do it. Yet among current humans, the future of kissing seems an open question. In our liberated era, have we become so quick to get past the kiss and further into lovemaking that we have devalued the icons, wisdoms and traditions of the ancestors? Have we diminished the meaning and memory of the lingering smooch, the languid summers of interlabial osculation spit-swapping lip-lock? If so, this is a horrifying situation. It must be stopped. Kissers of the world, unite!

"A kiss is a blast of information that you are sending out and information that you are receiving," says Helen Fisher, the Rutgers anthropologist who is the author of "Why We Love: The Nature and Chemistry of Romantic Love."

"Basically it's a mate assessment tool. Much of the cortex is devoted to picking up sensations from around the lips, cheeks, tongue and nose. Out of 12 cranial nerves, five of them are picking up the data from around the mouth. "It is built to pick up the most sensitive feelings -- the most intricate tastes and smells and touch and temperature. And when you're kissing somebody, you can really hear them and see them and feel them. So kissing is not just kissing. It is a profound advertisement of who you are, what you want and what you can give." "At the moment of the kiss, there are hard-wired mechanisms that assess health, reproductive status and genetic compatibility," says Gordon G. Gallup Jr., a professor of evolutionary psychology at the State University of New York at Albany who studies reproductive competition and the biology of interpersonal attraction.

"Therefore, what happens during that first kiss can be a make-or-break proposition."

For example, a woman can sense whether the man's immune system proteins are different from hers, thus increasing the odds of healthy offspring. "Women apparently are quite drawn to men who have differences rather than similarities in their histocompatibility system. They pick it up by smell, and they can pick it up from kissing," says Fisher, who is also science adviser to Chemistry.com, a division of Match.com.

Kissing thus not only conveys serious evolutionary advantage. It can dramatically alter the outcome of Saturday night. A survey of 1,041 college students led by SUNY Albany's Gallup found that 59 percent of men and 66 percent of women reported at least once finding someone attractive only to discover after the first kiss that they were no longer interested.

"I think we have evolved three distinctly different brain systems for mating and reproduction," Fisher says. "One is the sex drive. The second one is romantic love -- that elation, the craving, the obsessive thinking -- and the third is attachment, the sense of calm and security you can feel with a long-term partner.

"So what does kissing do? You're exchanging testosterone -- that can help to trigger the sex drive. If it's exciting and novel, it's likely to drive up dopamine -- that's associated with romantic love. And if it drives up oxytocin in long-term partners, it's triggering the attachment system. So any one of the three profoundly basic mating systems in the brain could be triggered by kissing."

Okay, but if kissing is all that important, why has kissing lost its iconic status? Why, according to the giant Gallup survey, do 52.9 percent of men and 14.6 percent of women (that high!) feel that they can readily skip the snog and dive right into the sack? Why, today, can you no longer imagine a movie being made like "Casablanca," which pivots on the question of whether "a kiss is just a kiss"?

The meaning of a kiss has varied over the centuries. Saint Paul told us to "salute another with a holy kiss." That rapidly got out of hand. "By the high middle ages, the 'holy kiss' was given or exchanged in Christian rituals of baptism, ordination, the consecration of bishops, coronations, absolution of penitents and in the marriage ceremony," historian Craig Koslofsky told New Scientist. During the Reformation, Protestants found all this public kissing treacherous.

Nonetheless, public displays of affection in England 400 years ago remained bold even by our standards. Foreign visitors commented on women of the household greeting complete strangers with a kiss on the mouth. Compare that with today. In some quarters, you can't pay to get kissed. By all accounts, hookers avoid it specifically because it connotes attachment and intimacy.

There is still plenty of ritual kissing. The pope's ring. The cup at Wimbledon. The Blarney Stone. The dice. There are also therapeutic kisses -- on a boo-boo to make it better. Kisses of death -- "The Godfather." And theatrical kissing: the chivalrous hand kiss, the Hollywood air kiss. But those differ entirely from the legendary kisses of our previous century -- Burt Lancaster and Deborah Kerr in the surf and sand in "From Here to Eternity," oh my moon and stars.

Kisses used to be transformative. The prince kisses Sleeping Beauty! The princess kisses the frog!

Kisses used to be iconic: illustrious, definitive, for the ages. Rodin's statue. The sailor and the nurse in Times Square at the end of World War II. Lady and the Tramp finishing the spaghetti. The memorable kisses of this young century, by contrast, are mainly those that are remarkable for examining the edges. Think "Brokeback Mountain." Or Madonna and Britney. Or in "Twilight," dancing with death -- making it with a vampire.

Popular culture increasingly takes, at best, glancing interest in the meaning of a kiss. Harry Potter's first kiss was really meh. Kissing cute is for machines like WALL E and EVE.

Sure, Ryan Gosling and Rachel McAdams won the 2005 Teen Choice Award for best rain-soaked kiss in "The Notebook." But in 2006, in "The Lake House," Sandra Bullock and Keanu Reeves attempt a homage to the legendary 1946 three-minute kissing sequence between Cary Grant and Ingrid Bergman in Alfred Hitchcock's "Notorious." Their failure is an embarrassment. Its effect is entirely the opposite of the intent. It's like watching woodpeckers.

The biggest advance in film kisses in this generation is the "kiss cam." Any lull in a major sporting event, and the camera scans the crowd, zeroing in on two people who are supposed to be good sports and very publicly display their affection on the JumboTron. Office co-workers? People of the same sex? Hilarity ensues. "Staples at American sporting events are hot dogs, popcorn, and the 'kiss cam,' " writes "LastRow," a blogger on ArmchairGM. What does this mean? Has tonsil hockey officially become a sport like any other?

Popular music really knows how to make the meaning of kissing seem quaint beyond superfluous. "Hip-hop is more likely to be talking about oral sex than talking about kissing," notes Joe Levy, editor in chief of Blender, the music magazine whose readership skews young.

Pop tart Katy Perry's No. 1 Billboard tribute to the kiss last year proclaimed: I kissed a girl and I liked itThe taste of her cherry ChapStickI kissed a girl just to try itI hope my boyfriend don't mind it

This is not to say that just because pop lyrics have come a long way from "I Want to Hold Your Hand," kissing is history, Levy says. "Even in a casual hookup culture where people might advertise for assignations on Craigslist, a lot of said assignations start with kissing. "I'm not sure because we're talking about it less in pop lyrics, it happens less or is less important. What used to start with a kiss still starts with a kiss. You just hear exactly where it went after that."

Nonetheless, try this zeitgeist test: See if you can find anyone under 35 who knows that "playing post office" once was a kissing game for early adolescents. Apparently it now has even less meaning than that once intensely stirring at-the-door moment: the goodnight kiss.

Sealed with a . . .Ten things you should know about kissing:

About two-thirds of all humans, male and female, tilt their heads to the right when kissing. It does not matter whether they are left- or right-handed. Men think that kissing is a highly effective way to end a fight. Women think that's hooey. For once, the women are incorrect. "The evidence shows," Gallup says, that "kissing is so powerful for females that even though they deny it, once it occurs, they're so affected by a kiss . . ." That they're helpless in its grip? "Yup."

Remember those great standing kisses in old movies, where the girl demonstrates ecstasy by lifting her delicately shod tootsie behind her? That move was called "foot pop." Such as, "What we need here is more foot pop." The science of kissing is known as philematology. In use: "He spent his undergraduate years studying philematology."

More men than women describe a good kiss as one that involves tongue contact, saliva exchange and moaning. After a relationship is established, women are much more likely than men to use kissing to monitor the commitment. "There is good evidence that the frequency of kissing is a pretty good barometer of the status of a relationship," Gallup says.

Kissing, of course, is not all moonlight and roses. It is implicated in the spread of mononucleosis and oral herpes. The connection to meningitis and gastric ulcers is more distant but exists.

Very few creatures other than humans are great kissers. The marked exceptions are our close relatives the chimpanzees and bonobos. Chimps are huge believers in kissing-and-making-up after conflict. But bonobos need no excuse. In "Our Inner Ape," Emory University primatologist Frans de Waal tells of a zookeeper not used to working with that crowd. Upon accepting a kiss from one of his new friends, "The keeper was understandably taken aback when he felt the bonobo's tongue in his mouth," de Waal writes.

The kiss-off?

There is no doubt that as a recreational activity, kissing has competition. "The kids who are less advanced, not living life in the fast lane, dating later, being high school juniors before their first relationship -- those are the kids who are still rolling around on the couch, kissing," says Rosanne Tobey, a family therapist who is a frequent contributor to MomLogic.com. "The others, who are sneaking out of the house because some boy calls at some random hour of the night, well -- the one who sneaks out at 2 a.m. is not going to roll on somebody's couch. There are no studies, but definitely I see this split."

There are indeed few if any hard data, but that just underscores how far kissing has fallen, says Bill Albert, chief program officer of the National Campaign to Prevent Teen and Unplanned Pregnancy. "Kissing isn't categorized in this notion of what's intimate" in, for example, the Youth Risk Behavior Surveillance System of the Centers for Disease Control, Albert observes. "Nobody thinks kissing is worth noting."

Yet if you suggest to 20- and 30-something women -- most particularly women -- that they may have spent a lesser portion of their lives necking than previous generations, you encounter unexpectedly fierce resistance.Conduct the experiment yourself. Ask the decline-of-kissing question in the context of the celebrated "hookup" culture. Experience the ferocity.